Cook pasta in a large pot of boiling salted water according to package directions; drain and set it aside.
Sauté sausage, chicken, and onion in oil in a large sauté pan over medium-high heat until browned, 5–7 minutes. Add garlic, tomato paste, fennel seed, and pepper flakes; cook until fragrant, 2–3 minutes.
Deglaze the pan with wine, then stir in tomatoes, broth, vinegar, and bay leaf. Bring to a boil and simmer, 5 minutes.
Stir in cream cheese until melted. Spoon ragu over pasta and garnish with Parmesan and parsley.